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Date: Fri, 14 Mar 2008 09:00:49 -0700 From: Arjan van de Ven <arjan@...radead.org> To: Yan <rottled@...il.com> Cc: linux-kernel@...r.kernel.org Subject: Re: 2.6.22.6 - Discrepancy between running and on-disk kernels On Fri, 14 Mar 2008 10:51:43 -0400 Yan <rottled@...il.com> wrote: > Hello, > > I have been trying to compare the code from the on-disk compressed > kernel that was booted and the running kernel extracted > from /dev/kmem. I extracted the kernel's code from the disk image by > stripping the head.S and similar and gunzipping it, and extracted the > kernel from /dev/kmem by reading data between _text and _etext symbol > offsets. > > I then ran both through a disassembler and diff'ed the outputs. > Predictably, the disassembly was similar, but not identical. Some > instructions (e.g. bts) had a 'lock' prefix, where as others had a > 'nop' in its place. > > There were other differences with some instructions like mfence. > Everything else matched just fine, the differences were mostly in > memory-referencing instructions. > > My question is, what can be changing the kernel between being on > static storage and being loaded? the kernel code is self-patching, it gets modified to match your system during boot time. So you cannot assume that the kernel on disk and the kernel in memory are identical. (Same goes for modules) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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